ABSTRACT: Estimating the impact of bank mergers requires a framework distinguishing endogenous changes in market structure and conduct from exogenous changes. Conventionally, the literature relies on differential analysis, considering market structure as exogenous by using concentration indexes such as the HHI. We introduce an econometric methodology relying on a structural model of the credit market from which we derive a counterfactual scenario of what would have happened if mergers had not occurred. We find that mergers increased firms' access to credit, but had an opposite effect on households. Moreover, we find that mergers led to a widespread decrease in interest rates.